The present invention generally relates to transfer devices in which solid articles such as tablets, capsules, granules and powders are transferred efficiently along a transfer face of a helical vane provided in a cylindrical member without causing damage to the solid articles. More particularly, this invention relates to a transfer device in which the fluidity of the solid articles is raised and moisture absorption of the solid articles is prevented during their transfer, while also facilitating efficient removal of dust or other foreign particles, mixed into transfer space, and efficient rinsing and drying of the transfer device at the time of its maintenance.
Generally, in production processes of solid articles such as granules and powders, the solid articles are transferred horizontally, upwardly or downwardly and between neighboring production processes. Meanwhile, since the surfaces of pharmaceutical tablets or capsules are readily damaged by external force applied during their transfer so as to be subjected to cracks or chips and since the entry of foreign matter into the pharmaceutical tablets or capsules should be prevented such that strict quality level of the pharmaceutical tablets or capsules is required to be maintained, great care should be given to their transfer.
Conventionally, in order to transfer solid articles such as tablets, mechanical transfer devices have been employed and include a bucket conveyor, an inclined belt conveyor and a brush conveyor disclosed, for example, in Japanese Patent Publication No. 3-13153 (1991).
As shown in FIG. 1, the prior art bucket conveyor includes a number of buckets 202 mounted on a vertically circulating conveyor 201. Solid articles supplied from a discharge opening 204 of a preceding process 203 are received by a bucket 202 disposed below. Bucket 202 is then conveyed upwardly by a belt conveyor 201 such that the solid articles accommodated in the bucket 202 are discharged to a supply opening 207 of the next process 206.
However, in the prior art bucket conveyor, since the solid articles are supplied into or discharged from the bucket, the solid articles are readily subjected to impact at the time of their supply or discharge so as to be damaged on their surfaces, thereby resulting in a risk of cracks or chips of the solid articles. Therefore, it is especially difficult to use the prior art bucket conveyor for transfer of pharmaceuticals. Meanwhile, disassembly, assembly and maintenance of the bucket conveyor cannot be performed easily. Furthermore, it is extremely difficult to rinse the bucket conveyor in its assembled state and the bucket conveyor cannot be rinsed with water. Hence, when solid articles of one kind are replaced by solid articles of another kind, mutual contamination may take place. Therefore, troublesome cleaning operation, in which several workers manually wipe over the bucket conveyor for a long period of time is necessary. Thus, the replacement of the solid articles of one kind by the solid articles of another kind is not easy. In addition, since a transfer path of the solid articles opens outwardly, the bucket conveyor can be neither converted to in-line application nor closed, thereby resulting in the risk of entry of foreign matter into the bucket conveyor.
As shown in FIG. 2, the prior art inclined belt conveyor 214 includes a supply portion 211 and a discharge portion 212, which are both disposed horizontally, and an upwardly inclined intermediate portion 213. Solid articles supplied from a preceding process 215, to the supply portion 211 disposed below, are transferred upwardly by the belt conveyor 214 and then, discharged from the upper discharge portion 212 to a supply opening 217 of the next process 216.
Disassembly and assembly of the prior art inclined belt conveyor 214 are also not easy. Furthermore, the inclined belt conveyor 214 in its assembled state cannot be rinsed with water. Thus, the prior art inclined belt conveyor 214 has drawbacks similar to those of the prior art bucket conveyor.
As shown in FIG. 3, the prior art brush conveyor includes an inclined cylindrical member 221 having a supply opening 223 and a discharge opening 225, formed at its lower portion 222 and its upper portion 224, respectively. A helical coil 226 is fixed to an inner surface of the cylindrical member 221 and a rotary brush 228 is rotatably provided along an axis 227 of the cylindrical member 221. Solid articles supplied into the supply opening 223 from a preceding process are pushed outwardly by the rotary brush 228 so as to be rotated along the inner surface of the cylindrical member 221. Since the helical coil 226 is fixed to the inner surface of the cylindrical member 221, the solid articles are transferred upwardly along the coil 226 so as to be discharged to the next process from the upper discharge opening 225. This prior art brush conveyor has the advantage of being easily converted into in-line application or being closed.
However, in the prior art brush conveyor, since the solid articles are depressed against the inner surface of the cylindrical member 221 during their transfer by the rotary brush 228, so as to be rubbed against the inner surface of the cylindrical member 221, the solid articles may be damaged on their surfaces. Accordingly, it is difficult to use the prior art brush conveyor for transfer of pharmaceutical tablets or the like. Meanwhile, in the prior art brush conveyor, if the solid articles penetrate into the rotary brush 228, so as to be brought out of contact with the coil 226, the solid articles are merely rotated about the axis 227 of the cylindrical member 221. Thus, the solid articles cannot be transferred upwardly along the coil 226. In other words, only a portion of the solid articles, those which remain adjacent to the inner surface of the cylindrical member 221, are transferred, thereby resulting in poor transfer efficiency.
Furthermore, in the prior art brush conveyor, since only a portion of the solid articles, are transferred upwardly, friction between the solid articles and the coil 226 must be increased. For example, in the case of sugar-coated tablets, if the angle of inclination of the cylindrical member 221 is set at 20.degree. or more, the solid articles cannot be transferred upwardly even if the number of revolutions of the rotary brush 228 is raised. In addition, since it is desirable that the friction between the solid articles and the coil 226 be minimized to prevent damage to the solid articles, high friction of the solid articles with the coil 226 for transferring the solid articles upwardly and low friction of the solid articles with the coil 226 for preventing damage to the solid articles are contradictory to each other. Consequently, in the prior art brush conveyor, if the solid articles are to be transferred without causing damage to the solid articles, the angle of inclination of the cylindrical member 221 cannot be increased.
Meanwhile, in order to solve the above mentioned problems of the conventional transfer devices, the applicant disclosed in, for example, Japanese Patent Application Nos. 6-211100 (1994) and 7-194587 (1995), shown in FIG. 4, a transfer device 230 which is capable of transferring solid articles, such as tablets, efficiently without causing damage to the solid articles, is closed as a whole so as to enable so-called in-line rinsing in its assembled state, which may be disassembled and assembled simply through reduction of the number of its components, and which may be easily maintained. This transfer device 230 includes a cylindrical member 232 having a supply portion 231 provided at one end, a central shaft 234 extending through an axis 233 of the cylindrical member 232 and a helical vane 235 provided around the central shaft 234. A transfer space 236 is defined between a peripheral surface of the central shaft 234 and an inner surface of the cylindrical member 232. A transfer face 237 is formed on one of the opposite faces of the helical vane 235 such that solid articles 238 supplied into the transfer space 236 from the supply portion 231 can be transferred along the transfer face 237 towards the other end of the cylindrical member 232.
As shown in FIG. 4, where the solid articles 238 are to be transferred vertically downwardly, the helical vane 235 is not required to be rotated. In other words, the solid articles 238 are gravitationally transferred while helically turning around the central shaft 234. On the other hand, where the solid articles 238 are to be transferred horizontally or upwardly, the axis 233 of the cylindrical member 232 is set to a transfer direction and the helical vane 235 is rotated about the axis 233 of the cylindrical member 232, so that the solid articles 238 are displaced along the central shaft 234 so as to be transferred.
In the known transfer device 230 referred to above, since the solid articles 238 are integrally transferred without much change of relative position, the solid articles 238 can be transferred efficiently without being subjected to external force such as impact force. Furthermore, since the transfer space 236 is covered by the cylindrical member 232, the transfer device 230 can be closed easily. Thus, in-line rinsing of the transfer device 230 can be performed. Furthermore, since the number of components of the transfer device 230 is quite small, maintenance, such as disassembly and assembly, can be performed easily. However, the known transfer device 230 has the following inconveniences (1) to (5).
(1) Since the solid articles 238 are displaced on the transfer face 237 formed on one face of the helical vane 235, the surfaces of solid articles 238 may be damaged if frictional force applied from the transfer face 237 to the solid articles 238 becomes extremely large. Such may be the case where the transfer rate of the solid articles 238 is increased.
(2) Where the solid articles 238 are formed by powder, the so-called bridging phenomenon of the powder may occur, thereby resulting in the risk of clogging the transfer space 236.
(3) Since the transfer space 236 is enclosed within the cylindrical member 232, the flow of ambient gas of the solid articles 238 is small. Therefore, the solid articles 238 are likely to absorb moisture due to the rise of humidity in the transfer space 236 and thus, may lose their superficial gloss or be deformed. For example, when humidity reaches 80%, the external appearance of sugar-coated tablets may be injured due to dissolution of the surfaces of the sugar-coated tablets or loss of gloss of the of the sugar-coated tablets.
(4) Since the flow of ambient gas of the solid 238 is small, it is difficult to remove dust and other foreign matters mixed in between the solid articles 238.
(5) As the transfer face 237 is formed on one face of the helical vane 235, the helical vane 235 has corner portions in the vicinity of the central shaft 234. Since it is difficult to pass cleaning fluid and drying air through the corner portions, the corner portions of the helical vane 235 cannot be rinsed or dried easily.
Moreover, the present invention also relates to a transfer device acting as a supply device for supplying solid articles into a vessel which is provided with the supply device. More particularly, the present invention relates to a supply device for supplying pharmaceutical tablets such as sugar-coated tablets, uncoated tablets and film coated tablets, pharmaceutical solid articles such as granules, powders and capsules or solid articles such as candies into various vessels including transfer vessels such as a container, a tank and a flow bin, a tank, a drum, and a hopper and where the vessel is provided with the supply device.
Where pharmaceutical tablets, such as sugarcoated tablets, uncoated tablets and film coated tablets, pharmaceutical solid articles, such as granules, powders and capsules or solid articles, such as candies, are supplied into a container, the solid articles may strike a bottom of the container or impinge upon one another thereby resulting in failures, cracks or chips on surfaces of the solid articles. Especially in the case of pharmaceutical tablets, defects such as cracks and chips pose a serious problem. Accordingly, various attempts to mitigate the impact of the fall have been made.
For example, in a container 241 formed by a flow bin as shown in FIG. 5, a plurality of flat plates (baffles) 242 inclined towards a bottom 241b of the container 241 are provided in the container 241 at multiple stages from a supply opening 241a. Solid articles 243 are supplied into the container 241 from the supply opening 241a and fall to the bottom 241b while sequentially hitting the baffles 242. However, by adding baffles 242 the container 241 becomes structurally complicated. Furthermore, since the baffles 242 are required to be attached to the interior of the container 241 by welding, production costs of the container 241 rise. In addition, it becomes more difficult to rinse the container 241, even in its disassembled state. Meanwhile, it is impossible to prevent impacts even though the solid articles 243 fall onto the baffles 242. In addition, since the container 241 is not suitable for storing fine powder, it is difficult to use the container 241 for both pharmaceutical tablets and powdery solid articles.
On the other hand, a device shown in FIG. 6 is disclosed in Japanese Patent Laid-Open Publication No. 6-135522 (1994). This known device includes a cylindrical member 255 standing vertically from the vicinity of the bottom of a container (not shown). A plurality of screw members 257, each formed with a helical groove 256, are provided in the cylindrical member 255 so as to be spaced a predetermined interval from each other by a collar 258. Meanwhile, an upper lid 259 having an inlet 259a is mounted on an upper end of the cylindrical member 25S and a lower lid 260 having an outlet 260a is mounted on a lower end of the cylindrical member 255. Furthermore, openings 255a and 255b are formed at portions of a side wall of the cylindrical member 255, which correspond to the collars 258, respectively. Solid articles are supplied into the cylindrical member 255 from the inlet 259a. The solid articles are, in turn, guided by the helical groove 256 while being turned helically so as to fall into the container from the outlet 260a. When the solid articles have accumulated on the bottom of the container, the outlet 260a is closed by the accumulated solid articles. Thus additional solid articles supplied from the inlet 259a remain in the helical groove 256 of the lowermost screw member 257. If solid articles are further supplied into the cylindrical member 255 from the inlet 259a, the solid articles remaining in the helical groove 256 of the lowermost screw member 257 eventually reach the lower opening 255a and are, in turn, discharged from the opening 255a. If the solid articles are further accumulated in the cylindrical member 255 so as to close the opening 255a, the solid articles remaining in the helical groove 256 of the intermediate screw member 257 rise and thus, are discharged from the upper opening 255b. In the known device of FIG. 6, as the amount of accumulated solid articles increases, the solid articles are discharged sequentially first from the outlet 260a, then from the lower opening 255a and finally from the upper opening 255b.
However, in the device of FIG. 6, since the solid articles still must fall into the container or out of openings 255a and 255b, the solid articles may be subjected to cracks or chips in dependence of their strength. In this device, the solid articles are not discharged into the container until the solid articles remaining in the helical groove 256 reach the upper opening 255b after the outlet 260a and the lower opening 255a have been closed by the accumulated solid articles. Furthermore, in this device, based on conditions such as size of the openings 255a and 255b, positions of the openings 255a and 255b, the type of the solid articles to be supplied, the amount of the solid articles supplied per unit period, a phenomenon may occur in which the solid articles fall into the container from the openings 255a and 255b before sufficient solids have accumulated at outlet 206a. If the solid articles fall from the openings 255a and 255b as described above, the solid articles may be subjected to failures, cracks and chips.
Furthermore, in this device, since the only portions of the cylindrical member 255 which remain open are the inlet 259a, the outlet 260a, and the openings 255a and 255b little ventilation in the helical groove 256 occurs, so that the solid articles may be damped. Especially, in the case of sugar-coated tablets not subjected to sufficient cool drying after the coating process. In this case, the tablets may be damped according to ambient conditions such as temperature, so that water may condense on the coated surfaces of the tablets, thereby resulting in loss of gloss of the surfaces of the tablets. Another problem occurs printed if the solid articles are damped. A printed portion of one solid article may impinge upon a nonprinted portion of another solid article at the time of the fall so as to transfer the print of one solid article to a nonprinted portion of the other. Moreover, since the solid articles are discharged from a plurality of openings 255a and 255b, the amount of supply of tablets and the types of the usable tablets are restricted.
The device of FIG. 7, disclosed by application in Japanese Patent Laid-Open Publication No. 61-127420 (1986), shows a transfer device acting as a supply device which includes a helical chute 281 for guiding tablets and a lift means 282 for displacing the helical chute 281 upwardly while rotating the helical chute 281 in a predetermined direction. In this prior art supply device, the amount of solid articles accumulated in a container 283 increases as the lowermost position of the helical chute 281 is lifted, such that the falling distance of the solid articles is maintained at a predetermined value.
In the conventional supply device of FIG. 7, since the direction of discharge of the solid articles 273 into the container 283 changes in response to the rotation of the helical chute 281, the solid articles 273 are uniformly accumulated in the container 283. Moreover, since the solid articles 273 are discharged from a lower end of the helical chute 281 continuously, efficiency for supplying the solid articles 273 is excellent. However, since the lift means 282 and a control means for controlling the lift means 282 are required, the conventional supply device is structurally complicated. Thus, it is difficult to perform maintenance checks and production cost tend to be high.